It's like an advertising budget. The actual cost of things like hormones is very low compared to other medications. Yes it's very expensive to a normal person but compared to their entire budget it's small. Then because most insurance in the US is done through big employers the insurance company can put a little line like "trans inclusive" etc so the ultra PC HR departments will skim through various policies and make sure to mark those as acceptable. The big companies at the same time use that as a way to brag about how inclusive they are. Those policies might even cost more but they will push that cost off onto the employees.

I just heard a stat today that for a family of 4 over the lifetime of coverage, the insurance will cost that family over $900,000. This is rarely talked about because for most people you don't even see that as a real expense. Your employer pays some portion of that for you but in reality that's your money that's being siphoned off. For me personally I have a zero contribution insurance plan with my employer because they pay the whole thing. The issue is they don't even really tell you how much it is unless you press them on it or you ask for a raise.